Downloaded By: [Geier, David] At: 23:30 29 November 2007 Journal of Toxicology and Environmental Health, Part B, 10:575–596, 2007
Copyright © Taylor & Francis Group, LLC
ISSN: 1093-7404 print / 1521-6950 online
DOI: 10.1080/10937400701389875
A REVIEW OF THIMEROSAL (MERTHIOLATE) AND ITS ETHYLMERCURY
BREAKDOWN PRODUCT: SPECIFIC HISTORICAL CONSIDERATIONS
REGARDING SAFETY AND EFFECTIVENESS
David A. Geier1, Lisa K. Sykes2, Mark R. Geier3
1The Institute of Chronic Illnesses, Inc., 2CoMeD, Inc., and 3The Genetic Centers of America,
Silver Spring, Maryland, USA
Thimerosal (Merthiolate) is an ethylmercury-containing pharmaceutical compound that is 49.55% mercury and that
was developed in 1927. Thimerosal has been marketed as an antimicrobial agent in a range of products, including
topical antiseptic solutions and antiseptic ointments for treating cuts, nasal sprays, eye solutions, vaginal spermi-
cides, diaper rash treatments, and perhaps most importantly as a preservative in vaccines and other injectable bio-
logical products, including Rho(D)-immune globulin preparations, despite evidence, dating to the early 1930s,
indicating Thimerosal to be potentially hazardous to humans and ineffective as an antimicrobial agent. Despite this,
Thimerosal was not scrutinized as part of U.S. pharmaceutical products until the 1980s, when the U.S. Food and
Drug Administration finally recognized its demonstrated ineffectiveness and toxicity in topical pharmaceutical prod-
ucts, and began to eliminate it from these. Ironically, while Thimerosal was being eliminated from topicals, it was
becoming more and more ubiquitous in the recommended immunization schedule for infants and pregnant women.
Furthermore, Thimerosal continues to be administered, as part of mandated immunizations and other pharmaceuti-
cal products, in the United States and globally. The ubiquitous and largely unchecked place of Thimerosal in phar-
maceuticals, therefore, represents a medical crisis.
Thimerosal (Merthiolate) is an ethylmercury-containing pharmaceutical compound that is
49.55% mercury and that was developed in 1927. Thimerosal continues to remain a part of the
modern practice of medicine and a part of modern vaccines to this day. For decades Thimerosal
has been marketed as an antimicrobial agent in a range of products, including as topical antiseptic
solutions and antiseptic ointments for treating cuts, nasal sprays, eye solutions, vaginal spermicides,
diaper rash treatments, and perhaps most importantly as a preservative in vaccines and other inject-
able biological products, including Rho(D)-immune globulin preparations, despite evidence, dating
to the early 1930s, indicating Thimerosal to be potentially hazardous to humans and ineffective as
an antimicrobial agent. Unchallenged, it remained in U.S. pharmaceutical products until the 1980s
when Thimerosal began to be withdrawn because of its demonstrated infectiveness and toxicity in
topical pharmaceutical products. Ironically, while Thimerosal was being eliminated from topicals, it
was becoming more ubiquitous in the immunization schedule for infants and pregnant women.
The removal of Thimerosal from several childhood vaccines and Rho(D) injections was not com-
pleted in the United States until after the turn of the 21st century, and today Thimerosal remains in
numerous prescription and over-the-counter pharmaceutical products (Subcommittee on Human
Rights and Wellness, 2003) and the influenza vaccine, now routinely recommended for administra-
tion to infants and pregnant women (Advisory Committee on Immunization Practices, 2006).
Recent statements made by those holding national and global responsibility for vaccine safety
are difficult to reconcile with the known and published toxicity of Thimerosal and ethylmercury. For
example, Francois et al. (2005) from the World Health Organization (WHO) and the U.S. Centers
We thank Dr. Paul G. King for his invaluable help on the chemistry of mercurials and federal regulations, and for his general review
of this article.
This study was supported by the non-profit Institute of Chronic Illnesses (Silver Spring, MD) through a grant from the Brenen Horn-
stein Autism Research & Education (BHARE) Foundation (Elk Grove, IL).
David A. Geier has been a consultant in vaccine/biologic cases before the no-fault National Vaccine Injury Compensation Program
(NVICP) and in civil litigation. Dr. Mark Geier has been an expert witness and a consultant in vaccine/biologic cases before the no-fault
NVICP and in civil litigation.
Address correspondence to Mark R. Geier, MD, PhD, 14 Redgate Ct., Silver Spring, MD 20905, USA. E-mail: [email protected]
575
Downloaded By: [Geier, David] At: 23:30 29 November 2007 576 D. A. GEIER ET AL.
for Disease Control and Prevention (CDC) reported, “Thimerosal (or thiomersal) has been used for
a long time as an effective preservative in some vaccines, and a number of pharmaceutical and cos-
metic products. It has both bactericidal and fungicidal properties and has effectively been applied
to prevent contamination of opened, multidose containers . . . Thimerosal has been used for >60
years in infant vaccines and in other applications and has not been associated with adverse health
effects in the general population . . . Hence there is no stringent reason to stop the use of Thimero-
sal-containing vaccines in current immunization programs worldwide. The balance of risks and ben-
efits of these vaccines is very clearly positive” (p. 954–955).
Offit and Jew (2003), reported, “However, no data exist on the capacity of low-dose, chronic
exposure to ethylmercury to harm the developing nervous system . . . Parents should be reassured
that quantities of mercury . . . contained in vaccines are likely to be harmless on the basis of expo-
sure studies in humans or experimental studies in animals” (p. 1395, p. 1399).
It appears that government regulators in many cases did not analyze the potential impact of
mercury upon the fetuses and infants who were being exposed. In fact, alarmingly, they were not
even responsible for initially calculating the cumulative amount of mercury contained in the immu-
nization schedule. This article is a historical review of the literature concerning Thimerosal and its
ethylmercury breakdown product.
EARLY HISTORY OF THIMEROSAL
Kharasch (1928) of College Park, MD, working in collaboration with Eli Lilly and Company
(Lilly) at the University of Maryland, filed a patent for an alkyl mercuric sulfur compound in
Indianapolis, Indiana. In his patent Kharasch claimed that compounds such as Thimerosal were,
“well-suited for intravenous injection . . . [and] effective therapeutically as germicides.” Shortly
thereafter, with the declaration that Thimerosal was “well-suited” for administration to humans and
“effective” as a germicide, Lilly began to manufacture and market this new product.
Kharasch’s assertion of Thimerosal’s benign and therapeutic nature was merely the beginning of
its scientific assessment. Smithburn and his colleagues (1930) recorded observations made during
human clinical experiments using Thimerosal to try to treat meningitis victims. In this article, they
noted, “the treatment has remained essentially the same throughout the epidemic” (p. 779).
Smithburn and his colleagues (1930) then described the use of Thimerosal in an experimental effort
to treat the disease. Specifically, they stated, “Intravenous administration of antiseptic solution was
tried and found wanting despite the in vitro activity of the agent” (p. 779). Smithburn and his col-
leagues (1930) also reported that efforts were made to combat positive nasopharyngeal cultures
with Thimerosal. They detailed a procedure to address this source of infection, applying ephedrine
sulfate in each nostril followed by Merthiolate (1 part per 4000 strength) twice daily. It was noted
that, after the institution of this therapy, no nasopharyngeal cultures were positive. However, Smith-
burn et al. (1930) also noted that the treatment was “symptomatic.”
In light of the preliminary research upon Thimerosal, early concerns were raised about Thime-
rosal: “in view of our experience with the Merthiolate solution, we have to know pretty definitely
what to expect from Merthiolate ointment and jelly before they are put on the market” (Subcom-
mittee on Human Rights and Wellness, p. 58). It was felt, “Our experience with the solution ought
to serve as a warning and certainly in the face of that warning we ought not to advocate the use . . .
without some pretty definite evidence that we will not repeat our solution experience” (Subcom-
mittee on Human Rights and Wellness, p. 58).
Despite the concern, Powell and Jamieson (1931) subsequently noted, regarding the toxicity of
Thimerosal, “Toxicity in man. Merthiolate has been injected intravenously into 22 persons in doses
up to 50 cubic centimeters of 1% solution . . . The toleration of such intravenous doses indicates a
very low order of toxicity of Merthiolate for man. This information has been supplied through the
kindness of Dr. K.C. Smithburn of Indianapolis who has had occasion to use Merthiolate in a clini-
cal way. Dr. Smithburn stated in these cases ‘beneficial effect of the drug was not definitely proven.
It did not appear, however, to have any deleterious action when used in rather large doses intrave-
nously when all the drug entered the vein’” (p. 306).
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 577
Downloaded By: [Geier, David] At: 23:30 29 November 2007 These statements and conclusions by Powell and Jamieson (1931) have been cited over
many decades, and continue to this day, to be cited in defense of the questionable claims that
Thimerosal had a low potential toxicity in humans. Upon closer inspection, however, it is appar-
ent that significant information regarding the clinical trial experience with Thimerosal was not
published.
First, in their article, Powell and Jamieson (1931) failed to reveal that the subjects evaluated by
Smithburn and his colleagues (1930) had, in fact, had meningitis, and were not healthy, a revelation
that would have called into question Powell and Jamieson’s conclusions regarding the nontoxicity
of Thimerosal. It should be noted that Powell and Jamieson (1931) provided a table in which the
22 subjects injected with Thimerosal were identified. These subjects, based upon the information
provided in the table, received massive doses of mercury from intravenous administration of
Thimerosal. The table notes that approximately one-third of the patients were followed for only 1 d
after the therapy. The table failed to note, however, that most probably this follow-up period was so
short because these individuals died. The table also noted only one patient was followed for 62 d.
This maximum follow-up length of 62 d was far too short to accurately discern any chronic damage
produced by the mercury, because mercury toxicity manifests fully only several months after expo-
sure. The study was also flawed because any neurological and/or other damage observed was likely
attributed to the meningitis rather than the Thimerosal exposure. Additionally, Powell and Jamieson
(1931) specifically commented that they evaluated patients, in particular, for shock or anaphylaxis-
type immediate reactions to the administration of Thimerosal. It is important to note that these
outcomes are not typical of mercury toxicity in humans.
Second, it is also apparent that Powell and Jamieson (1931) failed to emphasize their disturbing
animal toxicity data. In fact, Powell and Jamieson (1931) had already determined that administra-
tion of low milligram doses of Thimerosal per kilogram body weight in several different animals was
acutely toxic and resulted in significant numbers of animals dying within days of exposure.
Regarding the reported conclusions reached by Powell and Jamieson (1931), it was even com-
mented that “Considering the type of patient involved, one might question these observations [the
appearance of no deleterious action] as providing adequate indication of any harmful effects of high
doses of Merthiolate in humans, in particular, more long term effects” (Subcommittee on Human
Rights and Wellness, p. 58).
Kharasch (1932) filed a new patent application in an effort to acknowledge the potential
dangers of the germicide/antiseptic he had developed. Kharasch (1932) stated in this second
patent, “I will describe my invention more specifically in connection with that one of such com-
pounds which is now in most general use. That is sodium ethyl mercuri-thiosalicylate, which is
known on the market as Merthiolate.” According to Kharasch (1932), when Thimerosal “is first
made, it is entirely bland, both to the skin and mucous membrane. However, it is found that on
standing . . . the solution loses its blandness and acquires certain burning properties; which make its
use as an antiseptic and bactericide less desirable.” In describing the chemical basis for Thimerosal’s
ability to acquire “certain burning properties,” Kharasch (1932) detailed an important discovery
regarding the decomposition products of Thimerosal. Kharasch (1932) recorded that if “such for
instance as for sodium ethyl mercuri-thiosalicylate, is allowed to stand, there is a dissociation of a
few of the molecules at the bond between the sulphur and the ethyl mercury radical, producing a
small quantity of resultant ions” and that, “However, on account of the invariable presence of oxy-
gen, and of a catalyst such as copper, the sulphur-containing ion. . .is oxidized to the di-thio com-
pound . . . The formation of the di-thio compound removes these sulphur-containing ions from the . . .
mixture . . . so that progressively more ionization of the alky mercuric sulphur compound occurs . . .
whThyedinsrtopxoryonlctoeiosnsdserespcsrureilbstseeninitniantnhteheexpcaseotselsunottioftnhthatetotmhfoeerrmcCu2rCHi 25iHo−nH5−sgH+sug+c+−h+−O−a−HsOCHb2.Hr”e5aS−kuHdbogs+we+qnu—epnrwotldhyui,ccKhthroaefraacTstchhwimi(t1ehr9o3tsh2ae)l
might mediate adverse reactions in humans. These observations are important because they dem-
onstrate knowledge that Thimerosal would break down, in fairly rapid order, to produce ethylmer-
cury hydroxide and thiosalicylate, and that the ethylmercury breakdown product was the one
mediating Thimerosal toxicity.
Downloaded By: [Geier, David] At: 23:30 29 November 2007 578 D. A. GEIER ET AL.
Nonetheless, Marks et al. (1932) from the Lilly Research Laboratories reported, “Merthiolate
(sodium ethyl mercuri thiosalicylate), an organic mercurial compound, seems to fulfill the require-
ments of a satisfactory disinfectant . . . This compound has been shown to possess active germicidal
properties, maintaining its effectiveness in the presence of media most nearly resembling the
tissues, such as serum agar and white clot or fibrin agar. It is readily soluble, possesses definite pen-
etration properties, and does not precipitate serum proteins. Merthiolate has a low degree of toxicity
for animals and human beings, does not hemolyze red blood cells, and does not injure sensitive bac-
terial antigens and antibodies. It has been found to stimulate tissue cell growth and healing” (p. 443).
By the 1930s, Thimerosal was promoted for uses beyond topical antiseptic application. For
example, Jamieson and Powell (1931) described Thimerosal as an efficient preservative in biological
products.
While the applications for Thimerosal were increasing, Kharasch (1935) later applied for a third
patent for “organo-mercuri-sulfur compounds.” In this patent, Kharasch’s acknowledgment of
Thimerosal’s ineffectiveness and adverse effects in clinical practice exceeds all of his previous state-
ments: “It is the object of my invention to stabilize more effectively than has heretofore been done
certain antiseptic and bactericidal . . . compounds, which without such stabilization tend to form
disassociation products and to thereby both lose their effectiveness as antiseptic germicides and to
develop certain medicinally undesirable properties.”
In 1935, some of the first serious safety concerns were raised regarding Thimerosal. Specifically,
researchers reported a “reaction in about 50% of the dogs injected with serum containing dilutions
of Merthiolate, varying in 1 in 40000 to 1 in 5000, and we have demonstrated conclusively that
there is no connection between the lot of serum and the reaction. In other words, Merthiolate is
unsatisfactory as a preservative for serum intended for use on dogs.” They also noted, regarding the
reactions observed in dogs following administration of Thimerosal-containing serums, that “in some
instances, the reaction is extremely severe.” It was concluded, “I might say that we have tested Mer-
thiolate on humans and find that it gives a more marked . . . reaction than does phenol or tricresol”
(Subcommittee on Human Rights and Wellness, p. 34–35). Additionally, Salle and Lazarus (1935)
determined that Thimerosal was 35.3 times more toxic for embryonic cells than for the bacterial
cells that Thimerosal was supposed to kill.
Soon after this 1935 publication by Salle and Lazarus, Cummins (1937) documented in the
literature the first reports of Thimerosal-induced poisonings in animal model systems. Specifically,
he described, “two sets of 7 flasks each were treated with an amount of Merthiolate varying in dilu-
tion from 1 to 100 to 1 in 10 million of the medium in each series. . . The guinea-pigs inoculated
with 1 c.cm. of the mixtures after 24 hours all died; the first of Merthiolate poisoning” (p. 962).
Welch (1939), of the U.S. FDA, expanded the evaluation of the toxic action of potential preser-
vatives, including Thimerosal, in mammalian tissue culture experiments. Welch (1939), when com-
paring the relative toxicity of Thimerosal with other germicide compounds such as phenol or
iodine, determined that Thimerosal was, by several orders of magnitude, the most toxic compound
tested.
In addition, Welch and Hunter (1940), again of the U.S. FDA, continued their previous
research by reporting on the toxicity indices of germicides with human and guinea pig blood. The
researchers determined the toxicity indexes for each germicide tested, by comparing the highest
dilution producing inhibition in human cells or in guinea pig cells with the highest dilution that was
bactericidal for staphylococci. Their experiments showed that Thimerosal was, in fact, considerably
more toxic for human cells than bacterial cells (toxicity index=5.7). Furthermore, it was observed,
among the 10 germicides tested, that Thimerosal had the ninth worst toxicity index. With regard to
Thimerosal, the researchers concluded, “It becomes obvious then that if any antiseptic destroys the
function of the leukocyte much more readily than it kills bacteria there is little hope that it act
efficiently as a chemotherapeutic agent” (p. 136).
Kinsella (1941) described a cases series of 13 patients with bacterial endocarditis that received
Thimerosal treatment. It was observed that all patients receiving the Thimerosal treatment died, and
that following autopsy, some of the patients were determined to have died of mercury poisoning
from the Thimerosal treatment. For example, one report recorded, “Female, aged 23. Onset: Sore
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 579
Downloaded By: [Geier, David] At: 23:30 29 November 2007 throat treated with sulfanilamide. Later fever and pain the left chest. Examination: Systolic murmur
second i.c.s left. Blood cultures: Non-hemolytic strep. 37 times 50 colonies per c.c. Clinical
Diagnosis: Subacute bacterial endocarditis pulmonic valve (congenital). Treatment: Merthiolate.
Autopsy: Healing pulmonary endarteritis—mercury poisoning” (p. 985). In light of determination
that the treatment with Thimerosal produced mercury poisoning in humans, the suggestion was
made to significantly limit Thimerosal exposure in humans due to its toxicity and potential hazards.
Despite the aforementioned concerns, however, large amounts of Thimerosal were purchased
by the United States Government, for use in the war effort, from 1941 to 1945. During this time,
the U.S. Army scrutinized the use of Thimerosal as a preservative in blood products. On 20 February
1941, the National Institutes of Health issued minimum requirements for normal human plasma,
indicating that a sufficient amount of a suitable preservative should be added to the product
(Kendrick, 1989).
In the first of several meetings of the Subcommittee on Blood Substitutes of the U.S. Army, it
was noted that the Blood Transfusion Association of New York found Thimerosal unsatisfactory as a
preservative (Kendrick, 1989). Specifically, it considered the instance from 1940 in which a large
percentage of liquid plasma containing 1:10,000 Thimerosal, which had been collected in New
York City, arrived in Britain, contaminated with viable organisms (Kendrick, 1989). At that time, a
publication that questioned Thimerosal as a “preservative” concluded:
In a recent study of protein sulfhydryl groups Hellerman, Chinard and Deitz point out that organo-
metallic compounds of the type R-Hg-X . . . form poorly dissociated protein mercaptides by combina-
tion of the organic mercurial with proteins and thiol groups. According to Fildes the formation of
such mercaptides is the basis for the bacteriostatic action of mercury. Such sulfhydryl groups are
present, however, not only in bacteria but in plasma and other proteins. Bacteriostatic action of such
organomercuric compounds in the presence of serum is therefore largely prevented by competition
of reactive groups on the serum proteins for the mercury. This presumably is the basis of the finding
that the ‘activity of a mercurial antiseptic in serum is reduced to 0.33–0.0007 percent of its activity in
saline.’ Ignoring these chemical facts can be responsible for very serious occurrences, such as the
arrival in England of plasma ‘preserved’ with 1:10,000 Merthiolate containing viable micro-
organisms . . . In our experience 1:10,000 Merthiolate has not been able to insure the sterility of
stored liquid plasma. The contaminations reported in this paper in plasma-saline mixture containing
1:10,000 Merthiolate are sufficient to be an argument against its use. The material found to be
contaminated when tested after its arrival in England is further evidence that 1:10,000 Merthiolate
cannot be considered the ideal preservative. (p. 1253)
Weighing these concerns, some of the subcommittee members argued that plasma was best
stored without any preservative at all; however, a recommendation to this effect was waived when
the subcommittee realized that commercial firms were not inclined to process plasma without a
preservative. Then, at the 3 November 1941 meeting of the subcommittee, Veldee reported on a
review of the literature, which had been delegated to Weiss and himself. He informed the subcom-
mittee that Thimerosal apparently had some bacteriostatic value and possibly some bactericidal
value. Nonetheless, Weiss was not willing to accept Thimerosal as a preservative unless a maximum
limit was set on the dosage of plasma due to toxicity concerns. He also stipulated that the symptoms
of mercurial poisoning must be published on the label of the can. The Fifth Revision of Minimum
Requirements for Liquid or Dried Plasma, 8 January 1945, stated, “There is no preservative bacteri-
cidal to all probable contaminants in concentrations not dangerously toxic in the maximum human
dose.” Subsequently, the Sixth through Ninth Revisions (15 April 1949 through 15 May 1952) pro-
hibited use of a preservative (Gibson, 1976; Kenrick, 1989).
Concurrently, Ellis (1943) published an article on the possible danger of using Thimerosal in
ophthalmic ointments. In his report evaluating this use of Thimerosal, Ellis (1943) observed,
“Merthiolate is capable of causing an inflammation of the mucous membrane in patients,” (p. 266)
and made a very strong recommendation, based upon his clinical experience and that of several
other physicians, considering the adverse effects of Thimerosal use. He disputed the acceptance of
Thimerosal in medicine. Referencing the potential ability of Thimerosal to produce permanent
Downloaded By: [Geier, David] At: 23:30 29 November 2007 580 D. A. GEIER ET AL.
damage in the patient during clinical use, Ellis proposed, “it may be advisable to withdraw this prod-
uct from the market” (p. 266). It is important to note that this recommendation was made more than
6 decades ago, after Thimerosal had been on the market for only approximately 10 years.
Ellis (1947) continued his work on Thimerosal, and subsequently reported on an even larger
case series of patients experiencing adverse reactions following application of Thimerosal. Based
upon his further clinical experiences, as well as those of his medical colleagues, Ellis (1947) once
again strongly rebuked those advocating the continued use of Thimerosal in clinical medicine, stat-
ing, “it may be dangerous to inject a serum containing Merthiolate into a patient” (p. 213).
Subsequently, Cogswell and Shown (1948) reported, “We have had recently the occasion to
observe a patient with a severe reaction to tincture of Merthiolate . . . which manifested a local and
general reaction” (p. 42). The authors also stated, “The patient was warned never again to use Mer-
thiolate solutions” (p. 43). Placing the experience of this patient in a larger perspective, the authors
stated, “Many severe reactions have been reported following the use of mercurial ointments and a
lesser number due to antiseptics containing mercurials” (p. 42). Cogswell and Shown (1948) even
dared to condemn their colleagues for their myopia in wrongly evaluating the therapeutic effects of
Thimerosal in the clinical setting:
When a reaction does result, it is important that it be recognized and the application of the drug ceased.
Many of the reported cases are similar in that in spite of a reaction to Merthiolate, its use was being con-
tinued as a means of therapy to alleviate the result of the application. Hollander reported on a nurse
who had severe dermatitis venenata for over two years due to continuous self medication with tincture
of Merthiolate. Improvement was noted on discontinuing its use . . . reaction should be recognized to
prevent further applications of the drug which would exacerbate or accentuate the illness. (p. 43)
Morton et al. (1948), under a grant from the Council on Pharmacy and Chemistry of the
American Medical Association, published an article on the bacteriostatic and bactericidal actions of
some mercurial compounds on hemolytic streptococci. They reported:
The label on a bottle of ‘Solution Merthiolate, 1:1,000, Stainless’ purchased as recently as June 1947
states that it is ‘a stable, stainless, organic mercury compound of high germicidal value, particular in
serum and other protein media.’ It is not highly germicidal and especially does not possess high ger-
micidal value in the presence of serum and other protein mediums. The loss of antibacterial activity
of mercurials in the presence of serum proves their incompatibility with serum . . . The comparative
in vitro studies on mercurochrome, metaphen and Merthiolate on embryonic tissue cells and bacterial
cells by Salle and Lazarus cannot be ignored. These investigators found that metaphen, Merthiolate and
mercurochrome were 12, 35 and 262 times respectively more toxic for embryonic tissue cells than
for Staphylococcus aureus. Nye and Welch also found the same three mercurial compounds more
toxic for leukocytes than for bacterial cells. Not only is there direct toxic action of the mercurial com-
pounds on the cellular and humoral components of the animal body, but there is also the possibility
of sensitization. (p. 41)
Engley (1950) of the Biological Department, Chemical Corps, Camp Detrick, published an evalua-
tion of mercurial compounds as antiseptics and judged mercurials to be inadequate as antiseptics:
Mercurial compounds have not enjoyed a peaceful career as antibacterial chemicals since their pop-
ularization as germicides over sixty years ago (Kock, 1891) . . . During the ensuing years, other work-
ers, using various techniques, have also shown that the antibacterial activity of mercurials is only
slowly bactericidal and mainly bacteriostatic. This bacteriostasis is even nullified by the presence of
many types of sulfur-containing compounds, including sulfides (Geppert, 1889), (Hunt, 1937),
thioglycollate (Marshall, Gunnison, and Luxen, 1941), body fluids such as plasma (Johnson and
Meleney, 1942), and other organic matter (Green and Birkeland, 1944). (p. 197)
Furthermore, and of even greater concern, was Engley’s conclusion that mercurials, such as Thime-
rosal, “are ineffective in vivo and may be more toxic for tissue cells than bacterial cells, as shown in
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 581
Downloaded By: [Geier, David] At: 23:30 29 November 2007 mice (Nungester and Kempf, 1942) (Saber, 1942) (Spaulding and Bondi, 1947), tissue culture (Salle
and Catlin, 1947), and embryonic eggs (Witlin, 1942) (Green and Birkeland, 1944), and with leuco-
cytes (Welch and Hunter, 1940)” (p. 197).
Davisson et al. (1956) from the Lilly Research Laboratories reported on a molecular mechanism
for Thimerosal induced cellular toxicity. Specifically, they described that the cellular toxicity of
Thimerosal was the result of “partial ionization of the compound to go give a low but effective level
of ethyl mercuri ion (C2H5Hg+), which blocks enzymatic processes by combining with sulfhydryl
groups on the enzymes” (p. 8).
Subsequently, Engley (1956) presented a paper to the 42nd midyear meeting of the Chemical
Specialties Manufacturer’s Association in Chicago. Engley overtly questioned the acceptance of
Thimerosal as a preservative in vaccines and other pharmaceuticals products by stating:
The use of mercurials as preservatives in vaccines and antisera is of considerable interest. These
chemicals are added to protect against the introduction of organisms in multi-use containers in par-
ticular. We have always wondered about their efficacy in that both vaccines and antisera contain
reactive groups to tie up these compounds. In a series of continuing experiments over the past sev-
eral years we have begun to evaluate various preservatives in serum and vaccines under conditions
of use. Employing stock vaccines and serum with and without preservatives and stored at varying
lengths of time a contaminating dose of representative sporeformer (Bacillus subtilis) in the spore
stage gram negative rod (E. coli) and gram positive coccus (S. aureus) were added. While the mercu-
rial preservatives had good activity on initial addition, after storage of three, six or more months
decreasingly less to negligible residual activity appeared to be left, indicating that the chemical was
tied up by the protein of the biological or otherwise inactivated. A check on a series of over one
thousand bottles of various biologicals from clinics obtained after use revealed that up to five percent
contained micro-organisms. This would suggest that once these biologicals are in the hands of users a
problem still exists. Regarding preservatives, one of the real problems existing in hospitals and clinics
is the need for good preservatives in the routine eye dilators and nasal preparations of the deconges-
tant type. Routine checks of these indicate a high percentage of contaminated solutions. In one
instance we had direct evidence of upper respiratory cross-infection from the use of a common nasal
dropper preparation in a clinic. (p. 205, 223)
Engley (1956) then gave an evaluation of the relative toxicity of mercurials, such as Thimerosal,
by stating:
The toxicity of chemicals used as drugs on or in the body has been of considerable interest since man
first began exposing himself to various chemicals many years ago. Unfortunately there have not been
good techniques for toxicity determinations of certain types of chemicals which might be really indic-
ative of toxicity for humans . . . Graph 15 compares mercurial compounds and shows how they fit in
with other compounds in toxicity . . . Mercurochrome appears to be the least toxic ranging down
through Merthiolate . . . One point should be made here. Bichloride of mercury has always been
pointed out as an extremely toxic mercurial and the organic mercurials were supposed to be much
less toxic but according to these data we find bichloride right in the middle of the organic mercurials
in regard to cell toxicity . . . mercurial antiseptics proved to be more toxic than the antibiotics in
common usage. (p. 223–225)
Finally, it should be noted, with respect to the toxicity experiments undertaken by Engley (1956),
that he determined Thimerosal was significantly toxic to human tissue culture cells at a
concentration of 10 ppb.
PLANT AND ANIMAL MODELS OF ETHYLMERCURY TOXICITY
Interestingly, prior to studies conducted on the toxicity of ethylmercury in animals, a series of
studies was conducted to evaluate its toxicity to plants. Sass (1937) reported on the histological and
cytological pathology induced by ethylmercury poisoning in corn seedlings. Sass (1937) described,
“The use of dusts in which the active ingredient is ethyl mercury . . . produces a characteristic
Downloaded By: [Geier, David] At: 23:30 29 November 2007 582 D. A. GEIER ET AL.
malformation of the seedlings of corn and other cereals” (p. 95). He subsequently went onto
describe based upon his series of experiments:
In corn seedlings grown from nontreated seed, the leaf primordial and apical meristem of the
coleoptile have the structure characteristic of meristematic tissues. The cells are small, polygonal,
compactly arranged, and of uniform size. These cells are strictly uninucleate . . . Seedlings from treated
seeds exhibit varying degrees of distortion of cells, tissues and organs in proportion to the severity of
the gross external symptoms . . . The formation of new cells and new leaf primordial cases, the exist-
ing cells continuing their excessive irregular enlargement . . . The cells of the hypertrophied tissues of
corn seedlings were found to be multinucleate. The number of nuclei in a cell varies from one to
more than 10 . . . The ‘giant nuclei’ are clearly polyploid. (p. 95)
One of the earliest studies to evaluate the effects of ethylmercury on animals was published in
1950 (Trakhtenberg, 1950). In this study, the toxicity of the ethylmercury compounds was exam-
ined in mice. White mice were exposed to ethylmercury compound vapor, and the animals were
subsequently observed for clinical signs of toxicity and mortality. Those studies found:
Acute exposure to the organic mercury compounds caused symptoms indicative of serious respira-
tory and nervous system disruption: labored respiration, cyanosis of the nose, tail and ears, and hind
limb paralysis. All animals died 6 to 15 hours after exposure . . . In the chronic study, the central ner-
vous system was the main site of involvement. Mice exposed to the organic compounds showed a
hind limb paralysis that gradually spread to the front limbs. Death occurred by day 38. (p. 13–17)
Subsequently, researchers reported additional outcomes for an ethylmercury compound in
animals (Oliver & Platonow, 1960). These researchers reported that ethylmercury exposure,
“produced signs of central nervous system or gastrointestinal disturbance, or both in cattle . . . It
caused progressive degenerative changes in the heart . . . It produced diffuse lesions in the cord,
cerebellum, and cerebrum and caused glomerulonephritis” (p. 914–915).
The effects of ethylmercury poisoning were also observed in mass poisonings of swine on
several farms (Birbin et al., 1968). It was noted:
On the October’ Collective Farm in Tatishchevo District, 383 of 414 swine of various ages were
affected during August (1967), the acute period; 121 died and 145 in the agonal state had to be
slaughtered. By November, another 44 animals had died. On the Fedorov’ State Farm in Marx
District, 211 of 444 swine were affected . . . The first signs of poisoning appeared in suckling pigs and
fatling gilts 20 to 25 d after beginning feeding on the treated grain; in sows, the signs appeared in 30
to 40 d. At first, the animals refused food and water and became restless. There was some nasal
mucous secretion. Then weakness in the hind limbs appeared, with different types of movement
coordination disorder. Some animals showed spinal involvement. Signs of neural disorders were
quite clear, including muscular tremors, convulsional jerking of the extremities and titanic contrac-
tions of the pelvic musculature. As the conditions worsened, the animals lay on their stomachs or
sides, developing varying degrees of paralysis with loss of pain sensation, rapid breathing, etc. The
younger swine almost all died within 3 to 6 d after the symptoms started; the sows’ condition persisted
longer until death (6 to 11 d) and 40 to 45% of the affected animals died. In some instances, the swine
suffered the above symptoms, including partial or complete loss of vision, for 2 to 3 months. The
autopsy findings were initially the same in all the animals, the most constant changes being noted in
the intestines. The intestinal mucous membrane was covered with dryish, dirty yellow or brownish-
green deposits connected to the underlying tissue . . . The fact of a delay in the appearance of symp-
toms following Granosan must be taken into account in diagnosing organomercury poisonings. The
clinical symptoms and pathological-anatomical changes in mass poisonings of swine with Granosan
to a great extent recall the course of infectious diseases . . . so that mercury poisoning should be
eliminated during a differential diagnosis. (Birbin et al., 1968, p. 60–61)
Additionally, heavy losses were reported to have occurred in a poultry-yard due to feed treated
with ethylmercury (Tishkov et al., 1968). The clinical symptoms observed in chickens on the last
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 583
Downloaded By: [Geier, David] At: 23:30 29 November 2007 day before death were depression, spasm, paralysis of the limbs, swollen heads, and elevated
temperature. It was observed that mercury residues were detectable in the kidneys, liver, muscles,
skin, brains, lungs, hearts, ovaries, and eggs, and depending on the duration and intensity of the
exposure, mercury residues could be detected in the chicken tissues for as long as 120 d after the
poisoning.
Oharazawa (1968) published a study examining the ability of ethylmercury exposure during
pregnancy to induce fetal damage in mice. He observed that injection of ethylmercury during
pregnancy significantly reduced the weights of developing fetuses in utero and produced significant
increases in fetal malformations and the incidence of unstable chromosomes characterized as
polyploidy, chromatid gaps, or fragmented, in comparison to unexposed controls.
By 1971, researchers had become more sophisticated, evaluating the effects of ethylmercury on
several successive generations of offspring. Goncharuk (1971) administered an ethylmercury
compound to albino rats, and subsequently, these animals were mated. Investigations were made
of the sexual cycle, and the viability, physical development, and fertility of the progeny of the first
and second generations. It was observed that females that had been previously exposed to the
ethylmercury compound became pregnant only on the fourth or fifth occasion when they were
placed with males when in estrus, whereas nonexposed control females became impregnated on
the first or second mating. The number of offspring per litter was significantly smaller in the animals
treated with the ethylmercury compound than in controls. It was also observed that young rats from
mothers that had been previously exposed to the ethylmercury compound died significantly more
frequently than controls. Observations of the first-generation progeny revealed a lag in weight
growth in comparison to controls, especially during the first and second months of extrauterine life.
In addition, the first-generation progeny had birth weights that exceeded those of the control group,
and studies of skeletal ossification in the young rats revealed a large number of cases with retarda-
tion of the appearance and development of ossification centers in bones of the fore and hind paws.
Studies of the organs and tissues of the first generation progeny revealed mercury in the stomach
and intestine at birth and in the first week of life, apparently on account of the entry of mercury
through the placental barrier and by way of their mother’s milk. Subsequently, it was noted that the
first-generation progeny of mothers that had been previously exposed to the ethylmercury com-
pound had significantly reduced fertility in comparison to controls. The second generation progeny
had low viability, lagged in their weight growth, and were retarded with respect to ossification in
several cases. Finally, it was then observed when mating the second generation progeny that there
was a significant decrease in fertility in comparison to the control group.
A later study on pheasants by the Bureau of Sport Fisheries and Wildlife, Patuxent Wildlife
Research Center, concluded that ethylmercury compound exposure at a level equivalent to 12.5
ppm mercury was lethal to adult animals and at 4.2 ppm mercury impaired reproduction in the
species (Spann et al., 1972). These researchers also reported:
Ethyl mercury p-toluene sulfonanilide (active ingredient of Ceresan M) at a dietary concentration of
30 parts per million (12.5 parts of mercury per million) was lethal to adult ring-necked pheasants. Egg
production and survival of third-week embryos were sharply reduced when breeders were main-
tained on feed containing 10 parts of this compound per million (4.2 parts of mercury per million) . . .
Since similar residues of mercury have been found in eggs of wild pheasants and several species of
aquatic birds, we conclude that mercury pollution may be sufficiently high in some areas to affect
avian reproduction. (p. 328, 330)
Mukai (1972), with a grant from the U.S. National Institutes of Health, reported on an animal
model of ethylmercury-cysteine-induced encephalopathy using mice. Mukai (1972) observed:
Mice injected intraperitoneally with EMC (Ethyl Mercuri-S-Cysteine) labeled with tritium showed the
typical neurologic symptoms of mercury poisoning. Administration of EMC in a concentration of
0.3 mg/0.5 mL saline per day for at least eight days was a prerequisite for significant accretion of EMC
in the central nervous system. The extent and distribution of cell damage were highly predictable,
Downloaded By: [Geier, David] At: 23:30 29 November 2007 584 D. A. GEIER ET AL.
and selective necrosis of the small granular neurons in the koniocrotex, and neostriatum was a
constant finding. Autoradiographic study has suggested that the astroglial cell compartment plays a
role in conveying the mercury complex into neurons. (p. 102)
Subsequent research by Tryphonas and Nielsen (1973), which was sponsored by the Medical
Research Council of Canada, not only showed that ethylmercury produced a consistent and pre-
dictable pattern of encephalopathy, but also that it induced severe developmental toxicity at very
low doses. It was described:
Ethylmercuric chloride (EMC) w(as) used to produce chronic alkylmercurial poisoning in young pigs.
A dosage of 0.19 to 0.76 mg. of Hg/kg. of body weight per day was used . . . The resulting toxicosis
was primarily related to the nervous system, in which neuronal necrosis followed by secondary
gliosis, capillary endothelial proliferation, and additional neuronal necrosis due to developing degen-
erative arteriopathy in the blood vessels supplying injured gray matter were seen. In other systems,
degeneration of hepatocytes and renal tubular cells were commonly occurring lesions in pigs . . .
edema of the mescolon, necrosis of the epithelium, and degenerative arteriopathy in the submucosa
were seen most consistently in the esophagus and large intestine of pigs . . . The results proved that . . .
EMC, if fed at low concentrations . . . were highly poisonous . . . Finally, since the alkylmercurial
moiety is absorbed and stored as such for considerable lengths of time in . . . cells, the public health
implications . . . cannot be overlooked. (p. 379, 391)
Furthermore, Wright et al. (1973) from the U.S. Department of Agriculture evaluated the toxi-
cokinetics of mercury in the tissues of cattle and sheep administered ethylmercury. These researchers
showed that significant levels of mercury were detectable in multiple organs including the blood,
kidney, liver, and muscle for significant lengths of time following exposure to ethylmercury.
Additionally, these researchers found that mercury crossed the blood-brain barrier, and resulted in
significant levels of mercury in the brain for more than 20 wk (>140 d) following administration of
the last dose of this ethlymercury compound. In another study that examined swine administered
ethylmercury, it was found that significant levels of mercury were detectable for more than 8 mo
(>240 d) following administration of the last dose of the ethylmercury (Saley, 1970).
Yonaha et al. (1975), from the National Institute of Hygienic Sciences, also evaluated the
uptake, retention, and toxicity of ethylmercury in several organs, when administered to mice. These
researchers reported:
Ethylmercury chloride was highly incorporated into the brain . . . It may be presumed that manifesta-
tions of symptoms after exposure of organic mercury compounds is not merely related to mercury
levels and not always in need of organic forms in the brain . . . The clinical signs and pathological
findings caused by methylmercury compounds in animal experiments were known to be similar to
Minamata disease manifested in human. At the same time, the symptoms in cats, calves, and mice
poisoned by ethylmercury compounds were similar to those in methylmercury compounds. Further,
as reported by Sebe, et al., alkylmercury compounds having short carbon chains (C1-C3) bring about
the specific neurotoxicity and the signs of poisoning in rats. (p. 1718)
ETHYLMERCURY POISONING IN HUMANS
Spanning the 1950s and 1960s, a series of population outbreaks of ethylmercury poisonings
occurred in Iraq, following ingestion of Granosan M, an antifungal that was used to prevent plant
root disease in grain products. Beginning in 1955, the Iraqi Ministry of Agriculture supplied farmers
with seeds dusted with the fungicide. Farmers had been given frequent warnings against using the
treated seed for food, and as a result, most of them were aware of the highly lethal effect of eating
dusted seed. Out of ignorance or neglect, however, some unfortunate farmers and their families
consumed the seed and became the victims of mercury poisoning. Consequently, these farmers
developed a number of serious mercury-related conditions (Jalili & Abbasi, 1961; Al-Kassab &
Saigh, 1962; Dahhan & Orfaly, 1962; Damlugi, 1962). Specifically, it was reported:
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 585
Downloaded By: [Geier, David] At: 23:30 29 November 2007 Poisoning by a fungicide used for seed-borne diseases of cereals, ethyl mercury p-toluene sulfona-
nilide (Granoson M, Dupont) is described. It affected a large number of farmers and their families
who used the dressed seed in the preparation of home-made bread. Many systems were involved,
including the kidneys, the gastrointestinal tract, the skin, the heart, and the muscles, but involve-
ment of the nervous system was the most constant with disturbance of speech, cerebellar ataxia,
and spasticity. Mental abnormalities were occasionally observed . . . In 1956 many cases of mercury
poisoning were observed in the North of Iraq, and more than 100 cases were admitted to Mosul
Hospital with 14 deaths. In 1960, many farmers from the central part of Iraq were affected and 221
patients were admitted to one hospital in Baghdad. Other patients went to other hospitals. (Jalili &
Abbasi, 1961, p. 303)
Later, a significant series of patients in Russia was observed to suffer from serious toxic out-
comes following ingestion of ethylmercury and occupational exposure to ethylmercury (Shustov &
Syganova, 1970; Nizov & Shestakov, 1971). Early signs of exposure included general weakness,
pains, tachycardia, and headache. Thereafter, it was observed that appetite decreased until, at last,
food was refused; there was also nausea, liquid stool, disordered sleep, decreased memory, and
pain in the extremities. Most of the patients recovered, but death was observed following exposure
in some of the patients. Such case studies clearly demonstrate the severe toxicity of this compound
to humans and document its effect on multiple systems of the human body due to acute exposure.
Not only acute exposure, however, but also low-dose exposure has produced significant
impairment in human beings, a fact documented by Mukhtarova (1977). Mukhtarova (1977) exam-
ined the late after-effects upon the nervous system following chronic low-dose exposure to ethylm-
ercury. The researcher reported:
A total of 25 persons exposed to multiple effects of low ethyl-mercuric-chloride concentrations were
subjected to a clinical examination in dynamics 1 ½ and 3 years after exposure to the compound. In
investigations clinico-physiological (EEG, Asschner-Dagnini reflexes, etc) and biochemical (catechola-
mines, sugar, mercury, DDT, DDE in the urine, etc) methods were employed. The pathology of the
nervous system presented certain peculiarities by comparison with early period. In evidence were
changes in the simpatico-adrenal system function, vascular lesions of the brain after the type of tran-
sient derangements of the cerebral circulation in the vertebro-basilar basin and angiospasms, diffuse
changes in the nervous system with predominant involvement of the hypothalamic cerebral struc-
tures and in some cases psychiatric disturbances were on record. (p. 4–7)
Over time, further incidents of mercury poisonings by ethylmercury compounds continued to
offer substantial evidence and disclose a pattern of extreme toxicity produced by ethylmercury in
humans. For example, Cinca et al. (1980) reported on accidental ethylmercury poisoning with ner-
vous system, skeletal muscle, and myocardium injury and stated, “Four case reports are presented
of patients who ate the meat of a hog inadvertently fed seed treated with fungicides containing
ethyl mercury chloride. The clinical, electrophysiological, and toxicological, and in two of the
patients the pathological data, showed that this organic mercury compound has a very high toxicity
not only for the brain, but also for the spinal motor neurons, peripheral nerves, skeletal muscles,
and myocardium” (p. 143).
As another example, Zhang (1984) evaluated clinical symptoms observed in patients with eth-
ylmercury chloride poisoning and reported, “Forty-one patients in the Peoples Republic of China
were poisoned by ethyl mercury chloride, caused by the ingestion of rice that had been treated
with the chemical. A dose-response relationship was found. Five months after the onset of the
intoxication, the patients were still in poor condition” (p. 251).
Derban (1974) even reported on clinical symptoms observed in children following ethylmercury
poisoning of 144 people in a rural Ghana village, “Four children developed disturbance of speech
which led to stammering and scanning. Mental abnormality was observed in one boy who showed
occasional outburst of anger unrelated to circumstances. A girl developed encephalitis and became
completely paralyzed in both upper and lower limbs, with incontinence of urine and feces and
complete loss of speech” (p. 50).
Downloaded By: [Geier, David] At: 23:30 29 November 2007 586 D. A. GEIER ET AL.
Paramount in the historical scientific record of exposures to ethylmercury compounds are the
first reports of human fetal poisonings. Bakulina (1968) described in a study on a human fetal
poisoning:
Granosan (ethylmercury chloride) is capable of passing through the placental barrier and penetrating
into the fetus, causing in the organs of the latter grave pathological changes. The permeability of the
placental barrier for organic mercury compounds finds its confirmation in the presence of mercury in
the placenta and organs of the fetus . . . Breast feeding was found to be conducive to accumulation
of mercury in the organism of newborns, since the mothers’ milk, as a rule, disclosed the presence of
this element. A very important point was that fetal intoxication was possible for as long as 3–4 years
after the mother poisoned. (p. 63)
By the early 1970s, researchers developed an overall clinical picture of ethylmercury poisoning
in fetuses following large-scale ethylmercury poisoning episodes (Mal’tsev, 1972; Ramanauskayte &
Baublis 1973).
Ramanauskayte and Baublis (1973) stated that, after exposure to ethylmercury-treated seeds:
Intrauterine poisoning in infants was observed(.) . . . (C)hildren on the whole are more susceptible to
mercury than adults(.) . . . Serious functional disorders of the central nervous system, hydrocephalus,
cerebral paralysis, and spasms were observed in infants. Toxic encephalomyeloradiculoneuritis with
prevalence of the syndromes of lesions of the cerebral cortex, brain stem, cerebellum, myelitis, periph-
eral neurites, lesions of the motor centers, of the pyramidal tracts, and encephalitis with irregular alpha-
rhythm were observed . . . Epilepsy lasting up to 2 years was observed in 10% of all cases. Prevalence of
vegetoneurotic syndromes, tachycardia, bradycardia, arrhythmia, acrocyanosis, liability of the arterial
pressure, and reduction of the blood cholinesterase activity were found in older children with chronic
poisoning. The lesions of the liver, kidney, heart and gastrointestinal tract were much less pronounced
than those of the central nervous system. Sodium thiosulfate, glutamic acid, vitamin B and C com-
plexes, glucose, and diuresis are essential for detoxification. (Ramanauskayte & Baublis, 1973, p. 56–60)
Confirming the tremendous danger of ethylmercury compounds to children, Mal’tsev (1972)
reported that in cases of children poisoned with ethylmercury, the onset of symptoms usually
occurred many weeks following exposure. The first symptoms of ethylmercury poisoning in children
included asthenia, fatigability, and loss of appetite, followed by nausea, vomiting, liquid feces,
abdominal pains, and elevated temperature. Subsequently, the neurological syndrome developed
and consisted of symptoms such as ataxia, dysarthria, psychomotor disturbances, and sleep distur-
bances. The researcher reported that damage to the nervous system may be irreversible even fol-
lowing low-dose exposure. Mal’tsev (1972) also commented that, upon autopsy of children who
died of ethylmercury exposure, degenerative, inflammatory, and necrotic alterations were seen, as
well as hemorrhages in the central nervous system, kidney, liver, heart, and intestines. Mal’tsev
(1972) also reported that ethylmercury appeared to be the most dangerous to the embryos during
the third and four months of pregnancy.
EMERGING EVIDENCE OF THE TOXICITY OF THIMEROSAL
More recent scientific examination and case studies have shown that Thimerosal is not only
toxic but also lethal at comparable levels, in humans and animals.
Nelson and Gottshall (1967) from the Division of Biologic Products, Bureaus of Laboratories,
Michigan Department of Public Health, published, “Pertussis vaccines preserved with 0.01%
Merthiolate are more toxic for mice than unpreserved vaccines prepared from the same parent
concentrate and containing the same number of organisms . . . An increase in mortality was
observed when Merthiolate was injected separately, before or after an unpreserved saline suspen-
sion of pertussis vaccine” (p. 590).
From 17–19 June 1971, an international conference and its associated advisory committee
reviewed the environmental toxicity from mercurials (Suzuki et al., 1973). One of the key areas
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 587
Downloaded By: [Geier, David] At: 23:30 29 November 2007 examined at this conference was the metabolic fate of ethylmercury salts, with a specific emphasis
on Thimerosal, in humans. That committee reported:
The toxic nature of ethylmercury has been considered to be fairly similar to that of methylmercury
salts. In the recommendations of the international committee on Maximum Allowable Concentration
for mercury and its compounds, ethylmercury was grouped with methylmercury. Reports on human
intoxication with ethylmercury salts have usually reported symptoms similar to those of methylmer-
cury, which is accentuated by the typical neurological symptoms, although there have been a few
reports that noted slightly different symptoms from the typical features of methylmercury poisoning.
In acute experiments on animals, ethylmercury has an LD50 similar to that of methylmercury salts and
a high neurotoxicity similar to that of methylmercury. (p. 209–210)
In addition, the report stated:
By using methods for estimating the inorganic and total mercury content of biological specimens, the
metabolism of ethylmercury salts was studied in man and animals. The [carbon–mercury bond] C−Hg of
ethylmercury salts was able to break fairly rapidly and to a great extent in men, who were patients and
were transfused with a commercial product of human plasma containing 0.01% (Thimerosal) sodium
ethylmercurithiosalicylate, and also in mice injected subcutaneously or intravenously with ethylmercu-
rithiosalicylate solution. The increasing level of inorganic mercury and its percentage to total mercury
content in the brain were quite distinguishable with post-injection time in mice, which resulted in longer
biological half-time of total mercury than that reported for methylmercury injection. (p. 209)
Itoi and his colleagues (1972) conducted a series of experiments to evaluate the reproductive
toxicity of Thimerosal in rabbits. They observed that injection of increasing doses of Thimerosal
(from 0.02 to 0.2% solutions) into pregnant rabbits resulted in significantly increased numbers of
dead fetuses (up to 18% of fetuses died following exposure) and increased fetal congenital anoma-
lies (up to 9.1% of fetuses developed congenital anomalies following exposure) in comparison to
rabbits injected with physiological saline.
Axton (1972) also reported on a series of 6 patients (4 children and 2 adults), 5 of whom died
following injection with chloramphenicol preserved with abnormally high levels of Thimerosal. He
reported that there was something wrong with the chloramphenicol injections. This problem was
first suspected on 23 October 1969, following the appearance of skin necrosis over the injection
sites in 4 children, and the drug was withdrawn from the pediatric wards. Preliminary investigation
of the vials used, for pH, concentration of chloramphenicol, and bacteriology, revealed no abnor-
mality. Heavy metal contamination was not considered at this stage.
Case 1 was the first to die (6 November 1969), and on the morning of his death, the combina-
tion of albuminuria and glycosuria with mental symptoms suggested poisoning, possibly by a heavy
metal. The suspicion was supported by the necropsy findings later in the day (large swollen
kidneys). Reference was again made to the local manufacturers of the chloramphenicol, and it was
discovered that 0.51 kg of Thimerosal was used in the preparation of one thousand 1-g vials of
chloramphenicol. The correct amount should have been 0.51 g. The amount of Thimerosal in each
vial was 1000 times too much.
The FDA undertook a comprehensive review of the safety and effectiveness of over-the-counter
(OTC) medicines in 1974. As one facet of this review, a panel of experts was assembled to review
the safety and efficacy of OTC drugs containing mercury. The Advisory Review Panel on OTC
Miscellaneous External Drug Products began its slow-paced review in 1975.
Independently of the FDA’s review, Gasset et al. (1975), under a grant from the US National
Institutes of Health, examined mercury distribution following administration of Thimerosal to
animals. They stated, “A comparison of topical and subcutaneous administration of Thimerosal to
rabbits shows that a substantial concentration of mercury was present in blood and tissues of the
treated animals and their offspring. Thimerosal was found to cross the blood-brain and placenta
barriers” (p. 52). These researchers also determined that administration of Thimerosal caused a
dose-dependent significant increase in fetal mortality.
Downloaded By: [Geier, David] At: 23:30 29 November 2007 588 D. A. GEIER ET AL.
Blair et al. (1975) also examined mercury distribution and form following administration of
Thimerosal to animals. In 1975, the authors reported that squirrel monkeys were dosed intranasally
with saline or Thiomersal (sodium ethylmercurithiosalicylate, 0.002% w/v) daily for 6 mo. The total
amounts of Thiomersal given during the 6 month period were 418 μg (low-dose group) and 2280
μg (high-dose group). This was equivalent to 207 μg mercury and 1125 μg mercury. The dose
differential was achieved by more frequent administration to the high-dose group. Mercury concen-
trations were significantly raised over control values in brain, liver, muscle, and kidneys, but not
blood. Concentrations were highest in kidneys, moderate in liver and lowest in brain and muscle.
Much of the mercury was present in the inorganic form (37–91%). The authors concluded that
“accumulation of mercury from chronic use of thiomersal-preserved medicines is viewed as a
potential health hazard for man” (p. 171).
The U.S. Veterans Administration and the U.S. National Institutes of Health funded research
published by Van Horn et al. (1977) that examined the toxic effects of Thimerosal on human tissue
culture cells. These authors commented:
Widespread use of the mercurial-containing preservative Thimerosal as an antibacterial agent in
ophthalmic drugs and solutions warranted an investigation into its possible cytotoxic effects on the
functional and ultrastructural integrity of the corneal endothelium. . .(scanning electron microscopy)
SEM and (transmission electron microscopy) TEM of the endothelium of corneas perfused with
0.0005 percent Thimerosal for 5 hours revealed condensed mitochondria, cytoplasmic vacuoles,
and cytoplasmic flaps at the apical end of the cellular junctions. Perfusion of higher concentrations
(0.001 and 0.005 percent) of Thimerosal in (glutathione bicarbonate Ringer’s solution) GBR resulted
in increases in corneal thickness after 2 hours and irreversible ultrastructural damage to the endothe-
lial cells by 5 hours. Corneas perfused with 0.01 and 0.1 percent Thimerosal in GBR showed a rapid
and immediate increase in corneal thickness and endothelial cell death and necrosis within 1 hour. It
is postulated that the mercury in Thimerosal becomes bound to the cell membrane protein sulfhydryl
groups, causing an increase in cellular permeability. These results suggest that the prolonged expo-
sure of the corneal endothelium to Thimerosal in the accepted antimicrobial dosage of 0.005 to
0.001 percent may result in functional and structural damage to the endothelium . . . It is therefore
concluded that ophthalmic solutions containing Thimerosal should not be used. (p. 273–274, 280)
Parry (1977) utilized yeast cultures for the detection of environmental mutagens using a fluctua-
tion test. He described:
A microbial fluctuation test, modified for the detection of environmental mutagens has been
evaluated using a number of strains of the yeast Saccharomyces cerevisiae. Auoxtrophic diploid
cultures of yeast which produce prototrophic colonies by both mitotic gene conversion and
mutation have been extensively utilized for the detection and evaluation of chemicals showing
genetic activity. A number of the yeast strains utilized were shown to be suitable for use in the
fluctuation test . . . The yeast strains respond to doses of mutagens at least a 100-fold lower than
that required in a conventional short exposure treat and plate experiment. In experiments involv-
ing the induction of mitotic gene conversion at the tryptophan-5 and histidine-4 loci in the flucu-
ation test significant increases in prototrophic cells were produced in the presence of . . . the
preservative Thiomersal (0.0001 μg/mL) . . . The results demonstrate that the fluctuation test pro-
vides an extremely sensitive assay for the detection of chemicals which show genetic activity in
yeast at non-toxic concentrations. (p. 165)
It should be noted that Parry (1977) observed Thimerosal induced significant genetic alterations in
yeast cells at a level <1 ppb.
Fagan et al. (1977) published a case series of children who were apparently poisoned by
Thimerosal. Fagan et al. (1977) reported, in a study funded by the National Institute of Environ-
mental Health Sciences of the U.S. National Institutes of Health, that between 1969 and 1975,
13 cases of exomphalos were treated by Thimerosal. The authors analyzed the mercury content
in tissues from 10 of the patients who had died. Upon reviewing the test results, the researchers
stated:
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 589
Downloaded By: [Geier, David] At: 23:30 29 November 2007 The results showed that Thiomersal can induce blood and organ levels of organic mercury which are
well in excess of the minimum toxic levels in adults and fetuses . . . Although Thiomersal is an ethyl
mercury compound, it has similar toxicological properties to methyl mercury and the long-term
neurological sequelae produced by the ingestion of either methyl or ethyl mercury-based fungicides
are indistinguishable. (p. 962–963)
The authors also emphasized, “the fact that mercury readily penetrates intact membranes and is
highly toxic seems to have been forgotten. Equally effective and far less toxic broad-spectrum anti-
fungal and antibacterial . . . antiseptics are currently available” (p. 964).
Also published in 1977 were the results of a large-scale prospective human epidemiological
study (the Collaborative Perinatal Project of the National Institute of Neurological and Communicative
Disorders and Stroke, the U.S. Public Health Service, and the U.S. FDA) on drug exposures during
pregnancy and their association with birth defects (Heinonen et al., 1977). This study reported:
Between 1958 and 1965, under the auspices of the National Institute of Neurological and Commu-
nicative Disorders and Stroke, a prospective study of over 50,000 pregnancies was undertaken with
the main objective of determining whether there are factors during pregnancy or delivery that are
related to the risk of cerebral palsy or other neurological outcomes. This study ultimately became
known as the Collaborative Perinatal Project. Among many items of data obtained, drug use was
recorded during pregnancy, and birth defects identified in the children were recorded subsequently.
With the growing realization that drugs are sometimes teratogenic, it became mandatory to evaluate
the data from the perspective . . . The purpose of this book is to present data on drugs used by
50,282 gravidae in relation to birth defects identified in children. (p. viii)
The conclusion of these researchers with regard to Thimerosal:
The measure of association presented is a standardized relative risk (SRR) with its 95% confidence
limits. The SRR is the ratio of the observed number to the expected number of malformed children.
Since the SRR takes into account potential confounding variables, it represents the best estimate of
the relationship between a drug and a malformation . . . Finally, thiomersal . . . was associated with
malformations overall and with uniform malformations. (p. 299, 313)
Specifically, it was determined that Thimerosal exposure during the first 4 mo of pregnancy was
associated with a statistically significant increased risk (SRR=2.69) for birth defects.
Anundi et al. (1979) described a molecular mechanism by which Thimerosal exposure rapidly
induced cellular oxidative stress and subsequent cellular lysis following glutathione depletion, and
that the addition of cysteine could reverse the cellular toxicity of Thimerosal. Specifically, it was
determined:
Compounds are known which interact with lipids and proteins in such a way that both lipid peroxi-
dation and protein alkylation have been considered a cause of toxicity . . . it has become evident that
(glutathione) GSH protects against protein alkylation and that electrophilic compounds which
deplete GSH may alkylate proteins. The main point in this communication is that cellular damage
following GSH depletion may be explained by lipid peroxidation which destroys the cell before the
alkylation of proteins, as a component of cellular damage, is expressed. (p. 45–46)
In 1980, the FDA’s Advisory Review Panel on OTC Miscellaneous External Drug Products finally
delivered its report to the FDA. It reviewed 18 products containing mercury and found them all
either unsafe or ineffective for their stated purpose of killing bacteria to prevent infections. In terms
of effectiveness, the panel stated, “mercury compounds as a class are of dubious value for anti-
microbial use” (Subcommittee on Human Rights and Wellness, 2003, p. 61). They also stated,
“Mercury inhibits the growth of bacteria, but does not act swiftly to kill them” (Subcommittee on
Human Rights and Wellness, 2003, p. 61). In fact, the panel cited a study, conducted in 1935, on
the effectiveness of Thimerosal in killing staphylococcus bacteria on chick heart tissue. The study
Downloaded By: [Geier, David] At: 23:30 29 November 2007 590 D. A. GEIER ET AL.
determined that Thimerosal was 35 times more toxic to the heart tissue it was meant to protect than
to the bacteria it was meant to kill. In terms of safety, the panel cited a number of studies demon-
strating the highly allergenic nature of Thimerosal and related organic mercury products. For exam-
ple, it cited a Swedish study that showed that 10% of school children, 16% of military recruits, and
18% of twins, and 26% of medical students had hypersensitivity to Thimerosal. They stated that
while organic mercury compounds, like Thimerosal, were initially developed to decrease the toxic-
ity of the mercury ion, Thimerosal was actually found to be more toxic than bi-chloride of mercury
for certain human cells (Subcommittee on Human Rights and Wellness, 2003, p. 61). By way of
summary, “The Panel concludes that Thimerosal is not safe for OTC topical use because of its
potential for cell damage if applied to broken skin, and its allergy potential. It is not effective as a
topical antimicrobial because its bacteriostatic action can be reversed” (Subcommittee on Human
Rights and Wellness, 2003, p. 61).
Despite the fact that the FDA expert committee found Thimerosal and other ethylmercury com-
pounds to be unsafe and ineffective for OTC products in 1980, the process to remove mercurials
from these products was excruciatingly slow. As a first step in the process, the agency published
Advanced Notice of Proposed Rules or Notice of Proposed Rules, publicizing the recommendations
of their Advisory Panel on OTC Miscellaneous External Drug Products to ban Thimerosal and other
mercurial-containing products in 1980, 1982, 1990, 1991, 1994, and 1995. No action was taken
on any of these occasions (Subcommittee on Human Rights and Wellness, 2003). Decisive action
from the FDA on the issue of mercury in OTC products would not come until 1998, 18 years after
its Advisory Panel first acknowledged Thimerosal’s “lack of safety” in topical ointments
(Subcommittee on Human Rights and Wellness, 2003).
COMMENTARY TO END THE MEDICINAL USE OF THIMEROSAL
Heyworth and Truelove (1979) undertook a study to evaluate the potential adverse effects of
Thimerosal-containing immune globulin preparations. These researchers found, “Merthiolate
contains an ethyl group directly joined to a mercury atom. Organic compounds containing an alkyl
radical directly attached to a mercury atom are more toxic to human subjects than are other types
of mercury compounds. Considerable accumulation of mercury occurs in tissues of mice injected
with ethyl mercury compounds, and in 1 human subject receiving intravenous infusions of
Merthiolate-containing plasma tissue accumulation of mercury was also observed” (p. 331). The
researchers went onto conclude:
For many years, Merthiolate has been known to have anti-microbial activity. When it was first intro-
duced as an anti-microbial preservative, little information about the fundamental biological effects of
organic mercury compounds was available. We should like to suggest that Merthiolate should now
be regarded as an inappropriate preservative for anti-lymphocytic globulin preparations and other
materials which are intended for administration to human subjects. (p. 333)
Matheson et al. (1980) published a case report of mercury-poisoning induced by long-term
injection of Thimerosal-containing gamma globulin. They found that the patient developed pink,
scaling, pruritic palms and soles, flushed cheeks, photophobia, irritability, a fine tremor, altered
sensation in his fingertips, and slowed nerve conduction velocity. These authors reported, “Most
commercially available gammaglobulin preparations contain Merthiolate (sodium ethylmercurithiosal-
icylate), a mercury-containing compound, which serves as a bacteriostatic agent. Thus, patients
receiving regular injection of gammaglobulin are potentially at risk for the development of mercury
toxicity. . . It would appear, therefore, that Merthiolate which is used as a preservative in a commer-
cially available gammaglobulin preparation represents a potential hazard to patients” (p. 153, 155).
Forstrom et al. (1980) also published warnings regarding the use of Thimerosal, this time in
vaccines: “Reactions can be expected in such a high percentage of Merthiolate-sensitive persons
that Merthiolate in vaccines should be replaced by another antibacterial agent” (p. 241).
Heyworth (1982) described:
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 591
Downloaded By: [Geier, David] At: 23:30 29 November 2007 During a study of the properties of two antisera which had been prepared against human
lymphoid cells, the present author found that one of the antisera was cytotoxic to lymphoid and
non-lymphoid cells(.) . . . This effect was attributable to the organomercurial compound Merthi-
olate, which had been added to the (antilymphocyte serum) ALS as a preservative . . . In the
opinion of the present author, Merthiolate should no longer be added to ALS or other materials
which are intended for use in human subjects. Tissue accumulation of mercury has been
observed. (p. 91)
It was reported in 1983, in an article titled “Mercury Poisoning in Child Treated with Aqueous
Merthiolate,” that administration of Thimerosal resulted in a child dying from mercury toxicity
(Anonymous, 1983). The article stated, “The Ohio Board of Pharmacy has received an investigative
report from the Ohio Department of Health’s Division of Epidemiology regarding the death of a
21-month old child due to mercury poisoning. The investigation strongly implicated the Thimerosal
solution as ‘the source of mercury’ that subsequently resulted in the child’s death since no other
source could be identified” (p. 523).
Kravchenko et al. (1983) questioned the use of Thimerosal in vaccines and its inexplicable
acceptance in light of mounting scientific evidence demonstrating its inherent toxicity. These
researchers found: “Our experiments show that Merthiolate in 1:10,000 titer can not only damage
cells in culture but also change their properties. . . Increased sensitivity to this mercury compound
has been frequently noted in medical literature, and deserves particularly close attention. Although
there are numerous clinical studies confirming Merthiolate’s damaging action on humans, [medical
and biological preparations] MBP preservation with it continues and is even recommended by
WHO” (p. 87–92). In regard to the use of Thimerosal in vaccines, the researchers concluded, “All of
the above show that Merthiolate usage for MBP manufacturing is inadmissible, especially in pediatrics
. . . . Vaccines must contain only specific substances, free of ballast. There is no way that cell
damage can cause not harmful sequelae in the body” (p. 87–92).
Hekkens et al. (1983) undertook an evaluation of the effectiveness of some preservatives in
inactivated human vaccines by application of the test described in the United States Pharmaco-
poeia (USP) XIX. These researchers described that five recommended strains as well as three strains
isolated from vaccines were used as test strains. It was observed that vaccines preserved with
Thimerosal did not fully meet the requirements for a vaccine preservative according to the criteria
established by the USP XIX.
Royhans et al. (1984) reported on mercury toxicity following pediatric Thimerosal ear irriga-
tions. With regard to the danger posed by mercurials, the researchers were expansive in stating:
Although aqueous Merthiolate has been used for years as a topical antiseptic, a recent review of its
use by the Food and Drug Administration resulted in its classification as ‘less than effective.’ Further-
more, two of the ingredients (Thimerosal and borate) in Merthiolate are toxic if absorbed or injected . . .
Symptoms of organic mercury poisoning chiefly involve the central nervous system, including
paresthesia of the mouth, lips, tongue, and extremities; speech disorders, with difficulty in articulat-
ing words; difficulty in swallowing; salivation; neurasthenia; inability to recall basic information;
emotional instability; ataxia; clumsiness; stupor; and coma . . . Reactions to mercury depend to a
large extent on the form of the chemical agent; its absorption, storage, and excretion; duration of
exposure; and individual susceptibility. Both inorganic and dissociable organic mercurials appear to
act by the same mechanism. Mercury ion reacts with sulfhydryl groups to form mercaptides, which
inactivate sulfhydryl enzymes and interfere with cellular metabolism . . . The blood–brain barrier, is
also more permeable to organic than inorganic mercury. There are definite individual differences in
sensitivity to the effects of mercurials. Some patients tolerate prolonged exposure without symptoms;
others have significant systemic signs and neurological disability with much less exposure. The
mercury in Merthiolate is a thiosalicylate compound that is converted to inorganic mercury more
rapidly than is methyl mercury. The organic compound itself is also easily absorbable, and undergoes
widespread tissue distribution. Toxicity may be related both to the biotransformation into inorganic
mercury and to the unchanged compound, both of which cause degenerative changes in the brain,
especially in the visual cortex and cerebellum, and proliferative changes throughout the cerebellar
cortex. (p. 311–312)
Downloaded By: [Geier, David] At: 23:30 29 November 2007 592 D. A. GEIER ET AL.
Winship (1985, p. 171) reported, “Multi-dose vaccines and allergy-testing extracts contain a mer-
curial preservative, usually 0.01% Thimerosal, and may present problems occasionally in practice. It
is, therefore, now accepted that multi-dose injection preparations are undesirable and that preserva-
tives should not be present in unit-dose preparations.”
Stetler et al. (1985) from the U.S. CDC also evaluated the use of Thimerosal as a preservative in
vaccines and found it to be unsatisfactory. The authors reported that Thimerosal was ineffective as a
vaccine preservative, and that giving more mercury than was present in a single Thimerosal-containing
vaccine might pose a health hazard to vaccine recipients. Evaluating the effectiveness of Thimerosal
as a preservative in vaccines, the authors stated: “Laboratory experiments in this investigation have
shown up to 2 weeks’ survival of at least one strain of group A Streptococcus in multidose DTP
(Diphtheria-Tetanus-Pertussis) vials. The manufacturer’s preservative effectiveness tests showed that
at 4°C, 4.5% of the challenge Streptococcus survived 14 d after inoculation into a multi-dose DTP
vaccine vial. At currently used concentrations, Thimerosal is not an ideal preservative” (p. 302–303).
The authors also made specific reference to the toxicity of Thimerosal: “However, because Thime-
rosal is an organic mercurial compound, higher concentrations might reduce vaccine potency or
pose a health hazard to recipients” (p. 303). Their recommendations regarding the use of multi-
dose vials with a Thimerosal preservative were as follows: “The Thimerosal preservative present in
DTP vaccine requires substantial time to kill organisms and cannot be relied upon to prevent trans-
mission of bacteria under conditions of practice when a vial is used over a short period. Instead, the
most important means of preventing abscesses secondary to DTP vaccination is to prevent contam-
ination by careful attention to sterile technique” (p. 303).
Furthermore, Cox and Forsyth (1988) recommended, “However, severe reactions to thiomersal
demonstrate a need for vaccines with an alternative preservative” (p. 229).
Digar et al. (1987) expanded the knowledge base regarding the marked toxicity of Thimerosal
to the developing fetus. The researchers reported:
A single dose of 0.1 mg of Ethyl-mercury-thiosalicylate (Thimerosal) was injected into the yolk sac of
chick embryos . . . Embryos were collected . . . It was found that 0.1 mg dose of Thimerosal was
lethal in 46.46%. Gross malformations like syndactyly, thinning of the abdominal wall, visceroptosis
and scanty feather, during Organogensis as well as in the later period, have been noted in 36.03% . . .
Significant change in the weight of embryo, crown–rump length, body and wing lengths were also
observed . . . However, there was no gross reduction in the size of brain as compared to that of the
control. The high incidence of lethality and malformations prove that organic mercury was transmit-
ted from the yolk sac to the embryo. The deleterious effects of mercurials on cells and tissues seem to
be due to action on a wide spectrum of enzymes by the organic mercury both on the surface and
within the cell. The enzymes particularly involved are−Na−K activated ATPase and also sulfhydryl
groups. Goldwater reported that mercury disrupts the normal function of mitochondria and
lysosomes. (p. 153, 157)
Withrow and his colleagues (1989), from the U.S. FDA, in keeping with the expanding circle of
scientists and physicians expressing ever-increasing concerns in regard to the use of Thimerosal as a
preservative, evaluated the cytotoxicity and mutagenicity of Thimerosal at preservative levels in a
tissue culture system. These researchers reported:
It is known that Thimerosal . . . present in lens care solutions sometimes cause(s) ocular irritation in
contact lens users. For example, Coward et al. (1984) reported that 33% of patients using lens care
solutions with Thimerosal . . . experienced solution intolerance . . . In vitro studies have shown that
preservatives are toxic to cultured human and rat corneal epithelial cells and toxic to isolated rabbit
corneas, and to intact rabbit eyes. (p. 385)
Additionally, these researchers described the impact of Thimerosal at the cellular level:
Cell survival and mutagenesis were measured using the L5178Y mouse lymphoma (TK +/−) system.
Cells were exposed to varying amounts of preservatives for 1 h at 37°C, and then aliquots were
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 593
Downloaded By: [Geier, David] At: 23:30 29 November 2007 irradiated with UVA radiation (during the exposure to the preservative). Cells were then assayed for
survival, and for mutagenesis at the thymidine kinase (TK) locus. In concentrations commonly found
in ophthalmic solutions . . . Thimerosal (was) toxic to cells, and Thimerosal was slightly mutagenic.
When cells were exposed to preservative and UVA radiation. . .the mutagenic activity of Thimerosal
was enhanced. (p. 385)
Nascimento et al. (1990) not only reported on a death following Thimerosal ingestion but also
warned of the widespread danger which Thimerosal posed. Specifically, they reported, “A case of
mercurial poisoning caused by ingestion of an organic mercurial compound, Thimerosal, found in
local antiseptic solutions. The clinical picture consisted of grave neurological symptoms which were
not reversed by penicillamine and resin administration despite rapid plasma level reduction of mer-
cury. We call attention to this case because of the widespread availability of antiseptic solutions
containing mercurial compounds” (p. 218).
Aberer (1991) reviewed the continued use of mercury in medicine. In his article, Aberer (1991)
was comprehensive in declaring the extent of the problem that Thimerosal represented in pharma-
ceutical products: “The presence of mercury in over-the-counter drugs for the eye, ear, nose,
throat, and skin; in bleaching creams; as preservative in cosmetics, tooth pastes, lens solutions, vac-
cines, allergy test and immuno-therapy solutions, in antiseptics, disinfectants, and contraceptives; in
fungicides and herbicides; in dental fillings and thermometers; and many other products, makes it a
ubiquitous source of danger” (p. 150). He then went on to document the systemic failure to
remove this toxin from pharmaceutical products, “Despite calls for abandonment and a general
prohibition in 1967, mercury is still listed in many pharmacopoeias, including that of the United
States . . . Thus mercury is still much more frequently used than is generally believed. This seems
incomprehensible because side effects are not only potentially disastrous but also numerous and
well documented.” In describing the numerous and well-documented side effects of the use of
mercury in medicine, he stated that these included “Neurologic and psychiatric symptoms, renal
toxicity, erythroderma, and other signs of poisoning,” (p. 150) and furthermore, “Knowledge of all
these side effects has been available for some time” (p. 150). He concluded by arguing, “Recom-
mendations not to use mercury salts in children or only on prescription are insufficient. Removal
from textbooks seems overdue . . . However, calls for their abandonment (as early as 1960) or
restricted use have not sufficed. Only a general ban and their removal from the pharmacopoeias
will be effective in stopping the use of these dangerous, outmoded substances” (p. 150).
Brunner et al. (1991) evaluated the effects of Thimerosal in an in vitro porcine brain tubulin
assembly assay. These researchers examined the influence of Thimerosal on different parameters
[lag-phase, polymerization velocity, end absorption (steady-state level), reversibility, and influence
on disassembly at 4°C]. It was observed that low concentrations of Thimerosal led to a rapid inhibition
of tubulin assembly and disassembly of microtubules.
Additionally, Seal et al. (1991), in their article on the case against Thimerosal, concluded,
“Thimerosal is a weak antibacterial agent that is rapidly broken down to products, including ethylm-
ercury residues, which are neurotoxic. Its role as a preservative in vaccines has been questioned,
and the pharmaceutical industry considers its use as historical” (p. 315).
Hilleman (1991) from the Merck Vaccine Task Force expressed a newly initiated internal con-
cern over the mercury exposure infants were receiving through standard immunizations. It was
expressed:
PROBLEM: The regulatory control agencies in some countries, particularly Scandinavia (especially
Sweden), but also U.K., Japan, and Switzerland, have expressed concern for Thimerosal, a mercurial
preservative, in vaccines . . . PUTTING THIS INTO PERSPECTIVE: For Babies: The 25 μg of mercury in a
single 0.5 mL dose and extrapolated to a 6 lb. baby would be 25× the adjusted Swedish daily allowance
of 1.0 μg for a baby of that size. The total mercury burden in a baby is unknown but it has been stated
that the blood level of a newborn may exceed that of the mother. If 8 doses of Thimerosal-containing
vaccine were given in the first 6 months of life (3 DPT, 2 HIB, and 3 Hepatitis B) 200 μg of mercury
given, say to an average size of 12 lbs., would be about 87X the Swedish daily allowance of 2.3 μg of
mercury for a baby of that size. When viewed in this way, the mercury load appears rather large. (p. 1, 5)
Downloaded By: [Geier, David] At: 23:30 29 November 2007 594 D. A. GEIER ET AL.
Lowe and Southern (1994) evaluated the antimicrobial action of various preservatives for vac-
cines. They described, “The preservative most commonly used is Thiomersal. Other preservatives
are being evaluated because: (i) this material has become difficult to obtain; (ii) the use of
mercury-containing compounds in medicinal products is considered potentially harmful; and
(iii) it has been found that some vaccine components are unstable in the presence of this material”
(p. 115). In light of these facts, the researchers undertook a series of experiments comparing the
antimicrobial activity of phenoxyethanol with Thimerosal in diphtheria, tetanus, and pertussis
(adsorbed) vaccine. It was observed, “Both chemicals were equally effective in inactivating chal-
lenge doses of Gram-negative and Gram-positive micro-organisms, as well as yeast” (p. 915). In
significant contrast to their concerns regarding the potentially harmful effect of mercury-containing
compounds, Lowe and Southern (1994) noted, “the low toxicity of phenoxyethanol in children
has been reported” (p. 915).
Lowell et al. (1996), from the Washington University School of Medicine, made overt the asso-
ciation between Thimerosal and mercury poisoning by evaluating the adverse effects resulting from
administration of Thimerosal-containing hepatitis B immunoglobulin (HBIG). They reported:
Preparations of HBIG use Thimerosal (a mercury derivative) as a preservative. We encountered
mercury toxicity, in a patient who received high-dose immunoprophylaxis . . . HBIG preparations
contain Thimerosal as a preservative, which contains 49% organically bound mercury. Previous
reports have demonstrated that administration of Thimerosal-containing products may lead to mercury
poisoning . . . Physicians should suspect mercury toxicity in patients receiving high-dose HBIG. (p. 480)
Overshadowing the recorded concerns of independent researchers and pharmaceutical
representatives is the critical and unheeded recommendation that pregnant women and newborn
children should be protected from the potential neurotoxic effect of mercury-containing pharma-
ceuticals issued internally within the FDA. In August 1998, a U.S. FDA internal “Point Paper” was
prepared for the Maternal Immunization Working Group. This document officially recommended,
“For investigational vaccines indicated for maternal immunization, the use of single dose vials
should be required to avoid the need of preservative in multi-dose vials. . . Of concern here is the
potential neurotoxic effect of mercury especially when considering cumulative doses of this compo-
nent in early infancy” (Subcommittee on Human Rights and Wellness, 2003, p. 36).
CONCLUSION
The high order of toxicity from Thimerosal and its ethylmercury breakdown product has been
known and published for decades. Nonetheless, Thimerosal remains in the drug supply, especially
in various vaccines manufactured both for the United States and globally. The ubiquitous and
largely unchecked place of Thimerosal in pharmaceutical products, therefore, represents a medical
crisis in the modern day. Reforms in the manufacture and the licensing of vaccines and other drugs,
which should have been accomplished proactively, had anyone properly assessed their mercury
content, must now be conducted, reactively, under significant systemic stress. With no warning,
recall, or ban of mercury in vaccines and other drugs as of yet, the victim of this mandated, unwar-
ranted, and massive mercury exposure is still an unsuspecting public, and most especially its unborn
and newborn children.
REFERENCES
Aberer, W. 1991. Topical mercury should be banned-dangerous, outmoded, but still popular. J. Am. Acad. Dermatol., 24:150–151.
Advisory Committee on Immunization Practices. 2006. Prevention and control of influenza: recommendations of the Advisory Commit-
tee on Immunization Practices (ACIP). Mortal. Morbid. Weekly Rev. 55:1–42.
Al-Kassab, S., and Saigh, N. 1962. Mercury and calcium excretion in chronic poisoning with organic mercury compounds. J. Fac. Med.
Baghdad 4:118–123.
Anonymous. 1943. Mercurials as ‘preservatives.’ J. Am. Med. Assoc. 122:1253.
Anonymous. 1983. Mercury poisoning in child treated with aqueous Merthiolate. MD State Med. J. 32:523.
THIMEROSAL AND ITS ETHYLMERCURY BREAKDOWN PRODUCT 595
Downloaded By: [Geier, David] At: 23:30 29 November 2007 Anundi, I., Hogberg, J., and Stead A. H. 1979. Glutathione depletion in isolated hepatocytes: its relation to lipid peroxidation and
cellular damage. Acta Pharmacol. Toxicol. 49:45–51.
Ardatova, A. N., Poloz, D., and Yakusheva, O. V. 1969. Toxic effects of Granosan. Veterinariya (Moscow) 46:56–58.
Axton, J. H. M. 1972. Six cases of poisoning after a parenteral organic mercurial compound (Merthiolate). Postgrad. Med. J. 48:417–421.
Bakulina, A. V. (1968). The effect of subacute Granosan poisoning on the progeny. Soviet Med. 31:60–63.
Birbin, S. S., Alekseeva, A., and Bulatov, A. A. 1968. The poisoning of swine treated with Granosan. Veterinariya 8:60–61.
Blair, A. M. J. N., Clark, B., Clark, A. J., and Wood, P. 1975. Tissue concentrations of mercury after chronic dosing of squirrel monkeys
with Thiomersal. Toxicology 3:171–176.
Brunner, M., Albertini, S., and Wurgler, F. E. 1991. Effects of 10 known or suspected spindle poisons in the in vitro porcine brain tubulin
assembly assay. Mutagenesis 6:65–70.
Cinca, I., Dumitrescu, I., Onaca, P., Serbanescu, A., and Nestorescu, B. 1980. Accidental ethyl mercury poisoning with nervous system,
skeletal muscle, and myocardium injury. J. Neurol. Neurosurg. Psychiat. 43:143–149.
Cogswell, H. D., and Shown, A. 1948. Reaction following the use of tincture of Merthiolate. Ariz. Med. 5:42–43.
Cox, N. H., and Forsyth, A. 1988. Thiomersal allergy and vaccination reactions. Contact Dermatitis 18:229–233.
Cummins, S. L. (1937). Merthiolate in the treatment of tuberculosis. Lancet 230:962–963.
Dahhan, S. S., and Orfaly, H. 1962. Mercury poisoning and electorcardiographic changes. J. Fac. Med. Baghdad 4:104–111.
Damlugi, S. 1962. Mercurial poisoning with fungicide Granosan M. J. Fac. Med. Baghdad 4:83–103.
Davisson, E.O., Powell, H. M., MacFarlane, J. O., Hodgson, R., Stone, R. L., and Culbertson C. G. 1956. The preservation of poliomyelitis
vaccine with stabilized Merthiolate. J. Lab. Clin. Med. 47:8–19.
Derban, L. K. 1974. Outbreak of food poisoning due to alkyl-mercury fungicide on southern Ghana state farm. Arch. Environ. Health
28:49–52.
Digar, A., Sensharma, G. C., and Samal, S. N. 1987. Lethality and teratogenecity of organic mercury (Thimerosal) on the chick embryo. J.
Anat. Soc. India 36:153–159.
Ellis, F. A. 1943. Possible danger in use of Merthiolate ophthalmic ointment. Arch. Ophthalmol. 30:265–266.
Ellis, F. A. 1947. The sensitizing factor in Merthiolate. J. Allergy 18:212–213.
Engley, F .B. 1950. Evaluation of mercurial compounds as antiseptics. Ann. NY Acad. Sci. 53:197–206.
Engley, F. B. 1956. Mercurials as disinfectants: Evaluation of mercurial antimicrobic action and comparative toxicity for skin tissue cells.
Chicago: 42nd Mid-Year Meeting of the Chemical Specialties Manufacturer’s Association.
Fagan, D. G., Pritchard, J. S., Clarkson, T. W., and Greenwood, M. R. 1977. Organ mercury levels in infants with omphaloceles treated
with organic mercurial antiseptic. Arch. Dis. Child. 52:962–964.
Forstrom, L., Hannuksela, M., Kousa, M., and Lehymuskallio, E. 1980. Merthiolate hypersensitivity and vaccination. Contact Dermatitis
6:241–245.
Francois, G., Duclos, P., Margolis, H., Lavanchy, D., Siegrist, C. A., Meheus, A., Lambert, P. H., Emiroglu, N., Badur, S., and Van
Damme, P. 2005. Vaccine safety controversies and the future of vaccination programs. Pediatr. Infect. Dis. J. 24:953–961.
Gasset, A. R., Itoi, M., Ishii, Y., and Ramer, R. M. 1975. Teratogenicities of ophthalmic drugs. 2. Teratogenicities and tissue accumulation
of Thimerosal. Arch. Ophthalmol. 93:52–55.
Gibson, S. T. 1976. Memorandum from Assistant to the Director, Department of Biologics, Food and Drug Administration, “Use of
Thimerosal in Biologics Production.” Washington, DC.
Goncharuk, G. A. 1971. Experimental investigations of the effect of organomercury pesticides on generative functions and on progeny.
Hyg. Sanit. 36:40–43.
Heinonen, O. P., Slone, D., and Shapiro, S. 1977. Birth defects and drugs in pregnancy. Littleton, MA: Publishing Sciences Group.
Hekkens, F. E. A., Polak-Vogelzang, A. A., and Kreeftenberg, J. G. 1983. The antimicrobial effectiveness of some preservatives in inacti-
vated human vaccines. J. Biol. Stand. 9:277–285.
Heyworth, M. F. 1982. Clinical experience with antilymphocyte serum. Immunol. Rev. 65:79–97.
Heyworth, M. F., and Truelove, S. C. 1979. Problems associated with the use of Merthiolate as a preservative in anti-lymphocytic globulin.
Toxicology 12:325–333.
Hilleman, M. R. 1991. Merck Memorandum, “Vaccine Task Force Assignment: Thimerosal (Methiolate) Preservative—Problems, Analysis,
Suggestions for Resolution.” Whitehouse Station, NJ.
Itoi, M., Ishii, Y., and Kaneko, N. 1972. Teratogenicities of antiviral ophthalmics on experimental animals. Jpn. J. Clin. Ophthal. 26:631–640.
Jalili, M. A., and Abbasi, A. H. 1961. Poisoning by ethyl mercury toluene sulphonanilide. Br. J. Ind. Med. 18:303–308.
Jamieson, W. A., and Powell, H. M. 1931. Merthiolate as a preservative for biological products. Am. J. Hyg. 14:218–224.
Kendrick, D. B. 1989. Blood program in World War II. Washington, DC: Office of the Surgeon General, Department of the Army.
Kharasch, M. S. 1928. Alkyl merucric sulphur Compound and process for producing it. US Patent 1,672,615.
Kharasch, M. S. 1932. Stabilized bactericide and process of stabilizing it. U.S. Patent 1,862,896.
Kharasch, M. S. 1935. Stabilized organo-meruri-sulphur compounds. U.S. Patent 2,012,820.
Kinsella, R. A. 1941. Chemotherapy of bacterial endocarditis. Ann. Intern. Med. 15:982–986.
Kravchenko, A. T., Dzagurov, S. G., and Chervonskaia, G. P. 1983. Evaluation of the toxic action of prophylactic and therapeutic prepa-
rations on cell cultures. III. The detection of toxic properties in medical biological preparations by the degree of cell damage in the
L132 continuous cell line. Zh. Mikrobiol. Epidemiol. Immunobiol. 3:87–92.
Lowe, I., and Southern, J. 1994. The antimicrobial activity of phenoxyethanol in vaccines. Lett. Appl. Microbiol. 18:115–116.
Lowell, J. A., Burgess, S., and Shenoy, S. 1996. Mercury poisoning associated with hepatitis-B immunoglobulin. Lancet 347:480.
Mal’tsev, P. V. 1972. Granosan poisoning in children. Feldsher Akush. 37:14–16.
Marks, H. H., Powell, H. M., and Jamieson, W. A. 1932. Merthiolate as a skin disinfecting agent. J. Lab. Clin. Med. 18:443–449.
Downloaded By: [Geier, David] At: 23:30 29 November 2007 596 D. A. GEIER ET AL.
Matheson, D. S., Clarkson, T. W., and Gelfand, E. W. 1980. Mercury toxicity (acrodynia) induced by long term injection of gammaglobulin.
J. Pediatr. 97:153–155.
Morton, H. E., North, L L., and Engley, F. B. 1948. The bacteriostatic and bactericidal actions of some mercurial compounds on
Hemolytic streptococci: In vivo and in vitro studies. J. Am. Med. Assoc. 136:37–41.
Mukai, N. 1972. An experimental study of alkylmercurial encephalopathy. Acta Neuropathol. 72:102–109.
Mukhtarova, N. D. 1977. Late sequelae of nervous system pathology caused by the action of low concentrations of ethyl mercury
chloride. Gig. Tr. Prof. Zabol. 3:4–7.
Nascimento, L. O., Lorenzi Filho, G., and Rocha Ados, S. 1990. Lethal mercury poisoning due to ingestion of Merthiolate. Rev. Hosp.
Clin. Fac. Med. Sao Paulo 45:216–218.
Nelson, E. A., and Gottshall, R. Y. 1967. Enhanced toxicity for mice of pertussis vaccines when preserved with Merthiolate. Appl.
Microbiol. 15:590–593.
Nizov, A. A., and H. M. Shestakov, H. M. 1971. Contribution to the clinical aspects of Granosan poisoning. Sov. Med. 11:150–152.
Offit, P. A., and Jew, R. K. 2003. Addressing parents’ concerns: Do vaccines contain harmful preservatives, adjuvants, additives, or
residuals? Pediatrics 112:1394–1401.
Oharazawa, H. 1968. Effect of ethylmercuric phosphate in the pregnant mouse on chromosome abnormalities and fetal malformation. J.
Jpn. Obstet. Gynecol. 20:1479–1487.
Oliver, W. T., and Platonow, N. 1960. Studies on the pharmacology of n-(ethylmercuri)-p-toluenesulfonanilide. Am. J. Vet. Res. 21:906–916.
Parry, J. M. 1977. The use of yeast cultures for the detection of environmental mutagens using a fluctuation test. Mutat. Res. 46:165–176.
Powell, H. M., and Jamieson, W. A. 1931. Merthiolate as a germicide. Am. J. Hyg. 13:296–310.
Ramanauskayte, M. B., and Baublis, P. P. 1973. Clinical picture and treatment of organomercurial pesticide poisoning in children. Pedi-
atriya Moscow 35:56–60.
Rohyans, J., Walson, P. D., Wood, G. A., and MacDonald, W. A. 1984. Mercury toxicity following Merthiolate ear irrigations. J. Pediatr.
104:311–313.
Saley, P. L. 1970. Evaluation of slaughter products from Granosan-poisoned animals. Veterinariya 46:102–103.
Salle, A. J., and Lazarus, A. S. 1935. A comparison of the resistance of bacteria and embryonic tissue to germicidal substances. Proc. Soc.
Exp. Biol. Med. 32:665–667.
Sass, J. E. 1937. Histological and cytological studies of ethyl mercury phosphate poisoning in corn seedlings. Phytopathologia 27:95–99.
Seal, D., Ficker, L., Wright, P., and Andrews, V. 1991. The case against Thiomersal. Lancet 338:315–316.
Shustov, V. I. A., and Syganova, S. I. 1970. Clinical aspects of subacute intoxication with Granosan. Kazansk. Med. Zh. 2:78–79.
Smithburn, K. C., Kempf, G. F., Zerfas, L. G., and Gilman, L. H. 1930. Meningococcic meningitis: a clinical study of one-hundred and
forty-four epidemic cases. J. Am. Med. Assoc. 95:776–780.
Spann, J. W., Heath, R. G., Kreitzer, J. F., and Locke, L. N. 1972. Ethyl-mercury-p-toluene-sulfonanilide: Lethal and reproductive effects
on pheasants Science 175:328–330.
Stetler, H. C., Garbe, P. L., Dwyer, D. M., Facklam, R. R., Ornstein, W. A., West, G. R., Dudley, J., and Bloch, A. B. 1985. Outbreaks of
group a streptococcal abscesses following diphtheria-tetanus-toxoid pertussis vaccination. Pediatrics 75:299–303.
Subcommittee on Human Rights and Wellness, Government Reform Committee (Chairman Dan Burton). 2003. Mercury in medicine—
Taking unnecessary risks. Washington, DC.
Suzuki, T., Takemoto, T. L., Kashiwazaki, H., and Miyama, T. 1973. Metabolic fate of ethylmercury salts in man and animals. In Mercury,
mercurials, mercaptans, eds. M. W. Miller and T. W. Clarkson, pp. 209–240. Springfield, IL: Charles C. Thomas,
Tishkov, A. L., Saley, P., and Vitkalov, V. P. 1968. Poultry poisoning with Granosan. Veterinariya 45:58.
Trakhtenberg, I. M. 1950. The toxicity of vapors of organic mercury compounds (ethlmercuric phosphate and ethylmercuric chloride) in
acute and chronic intoxication (experimental data). Gig. Sanit. 6:13–17.
Tryphonas, L., and Nielsen, N. O. 1973. Pathology of chronic alkylmercurial poisoning in swine. Am. J. Vet. Res. 34:379–392.
Van Horn, D. L., Edlehauser, H. F., Prodanovich, G., Eiferman, R., and Pederson, H. J. 1977. Effect of ophthalmic preservative Thimero-
sal on rabbit and human corneal endothelium. Invest. Ophthalmol. Visual Sci. 16:273–280.
Welch, H. 1939. Mechanism of the toxic action of germicides on whole blood measured by the loss of phagocytic activity of leucocytes.
J. Immunol. 37:525–533.
Welch, H., and Hunter, A. C. 1940. Method for determining the effect of chemical antisepsis on phagocytosis. Am. J. Public Health
30:129–137.
Winship, K. A. 1986. Organic mercury compounds and their toxicity. Adverse Drug React. Acute Poisoning Rev. 5:141–180.
Withrow, T. J., Brown, N. T., Hitchins, V. M., and Strickland, A. G. 1989. Cytotoxicity and mutagenicity of ophthalmic solution preserva-
tives and UVA radiation in L5178Y cells. Photochem. Photobiol. 50:385–389.
Wright, F. C., Palmer, J. S., and Riner, J. C. 1973. Retention of mercury in tissues of cattle and sheep given oral doses of a mercurial fun-
gicide, Ceresan M. J. Agric. Food Chem. 21:614–615.
Yonaha, M., Ishikura, S., and Uchiyama, M. 1975. Toxicity of organic mercury compounds. III. Uptake and retention of mercury in sev-
eral organs of mice by long term exposure of alkoxyethlmercury compounds. Chem. Pharm. Bull. 23:1718–1725.
Zhang, J. 1984. Clinical observations in ethyl mercury chloride poisoning. Am. J. Ind. Med. 5:251–258.